Nonionic surfactant-iodine composition



United States Patent F This invention relates to a novel composition of matter comprising a combination of iodine with a mixture of (1) a water-soluble nonionic surface active agent obtained by condensing an alkylphenol with ethylene oxide and (2) a water-insoluble nonionic surface active agent also obtained by condensing an alkyl phenol with ethylene oxide.

In British Patent 703,091 of Herman Shelanski there are described germicidal compositions comprising the combination of elemental iodine with a water-soluble nonionic surface active agent containing a polyglycol ether group. Included in the water-soluble nonionic surface active agents disclosed in said British patent are water-soluble nonionic surface active agents obtained by condensing an alkylphenol, such as nonylphenol, with ethylene oxide. Such combinations of iodine with watersoluble nonionic surface active agents are quite effective germicides and are finding increasing germicidal use. They are frequently referred to in the art as Iodophors which may be defined as: a mixture of iodine and a carrier in which the carrier is a compound which greatly increases the solubility of and tends to stabilize the iodine in aqueous systems to reactants other than microorganisms.

While water-soluble nonionic surface active agents have the ability to combine with, and solubilize, a relatively large amount of iodine, eg to by weight of iodine, it has been found that when such compositions containing an amount of iodine much over 10% iodine (e.g. 10 parts by weight of elemental iodine to 90 parts by weight of water-soluble nonionic surface active agent) are prepared, that there is a decided thickening of the normally viscous water-soluble nonionic surface active agent. As a result such products containing a relatively high proportion of iodine are difiicult to compound further in the formulation of various consumer type products containing them and as the iodine content approaches about 20% by weight they become viscous non-pourable pastes. Also, if they are prepared to be used alone they are more diflicult to measure than liquids and are somewhat slower to dissolve in water.

It has previously been suggested that the fluidity of compositions comprising a water-soluble nonionic surface active agent and iodine can be maintained, even when the composition contains a relatively high proportion of iodine, by incorporation in the mixture of a volatile solvent such as isopropanol (Sutton and Reynolds US. Patent 2,759,869). However, it will be apparent that such use of volatile solvents suffers from the disadvantage that the product again becomes pastelike should the solvent evaporate.

It has also been found that an acid environment is necessary to obtain the maximum biocidal efliciency of iodine in Iodophors comprising a combination of watersoluble nonionic surface active agent and iodine (Gershenfeld and Witlin, Evaluation of Iodine Sanitizers, Soap and Chemical Specialties, September and October 1956). The presence of acid in Iodophor compositions also has the advantage that it will combine with any alkali which may be present in the water used and thus serves to protect the iodine from being uselessly consumed. Therefore, in order to prevent unnecessary consumption or 2,989,434 Patented June 20, 1 961 loss of iodine in use and to assure the most efiicient medium in use, the Iodophors are preferably mixed with sufiicient acid to maintain the desired degree of acidity in the water present. While it appears that essentially any non-oxidizing acid such as hydrochloric acid, phos phoric acid, etc. may be combined with Iodophors; we particularly prefer to employ phosphoric acid since, in addition to its low toxicity and volatility, phosphoric acid has buifering action in the pH range from 3-4. The amount of acid employed in formulating consumer products containing Iodophors will vary depending both on the extent to which the product is to be diluted in use and also should be adjusted with respect to the alkalinity of the Water in which the product will be used.

It has also been discovered that when an Iodophor is formulated into a consumer product in which an Iodophor having more than 40% available iodine is diluted with water and acid that the product is unstable in that these will separate into two phases on standing.

It is, therefore, an object of the present invention to I provide an Iodophor composition consisting essentially of an alkylphenol-ethylene oxide nonionic surface active agent and iodine which remains fluid even when the amount of available iodine in such Iodophor is 20% or more. A further object of this invention is to provide an Iodophor composition comprising a combination of iodine and alkylphenol-ethylene oxide nonionic surface active agent which may be formulated into a preferred type of consumer product by addition of an acid and dilution with water and yield a stable product, i.e. one which does not form a precipitate or separate into two phases. A further object of the invention is to provide improved novel formulated consumer products com prising an acidified aqueous solution of an Iodophor consisting essentially of a combination of iodine and alkylphenol-ethylene oxide nonionic surface active agents.

We have discovered that if a mixture of (l) a watersoluble alkylphenol-ethylene oxide nonionic surface active agent with (2) a water-insoluble alkylphenol-ethylene oxide nonionic surface active agent is combined with free iodine that the thus obtained product remains a free flowing viscous liquid even when a relatively high amount of iodine, such as suflicient iodine to give 20% available iodine, is incorporated into it. We have further found that such Iodophors, comprising combination of iodine with a mixture of a water-soluble and a water-insoluble 'alkylphenol-ethylene oxide nonionic surface active agent, can be diluted with water and acid to give preferred consumer type formulations which are'stable and do not separate or deposit sediment.

In the novel Iodophors of the present invention, comprising a combination of iodine with a mixture of watersoluble and water-insoluble 'alkylphenol-ethylene oxide surface active agents, as in the prior art Iodophors consisting essentially of a combination of iodine with a watersoluble nonionic surface active agent containing a polyglycol ether group, not all the iodine combined with the carrier remains as bacteriologically active or available iodine.

The available iodine is defined as the iodine which is titratable by reason of its ability to oxidize sodium thiosulfate. Available iodine can be determined by titration with standardized thiosulfate, preferably using potentiometric titration rather than starch-end-point titration, because the presence of nonionic surfactant interferes with the starch end point. An ordinary pH meter with a millivolt scale will serve as a potentiometer. The details of a preferred method of analysis are as follows.

Reagent: 0.1 N standard sodium thiosulfate (Na S O Procedure: Weigh approximately 1 g. sample to the nearest milligram and dissolve it in approximately ml. distilled water. 7 This quantity is satisfactory for test 3 ing straight Iodophors; it will give iodine to consume approximately 15-20 ml. of sodium thiosulfate solution. In determining the available-iodine content of dilute Iodophor solutions, multiply this amount (1 g.) by the dilution factor.

Titrate the solution potentiometrically with the standard 0.1 N sodium thiosulfate, using a platinum vs. calomel electrode.

Calculation:

Percent available iodine ml. Na S O Xnormality Nilgsgogx grams of sample The total iodide can be determined by the Volhard method after reduction of the available iodine with bisulfite; specific details of this method are as follows:

Reagents:

0.1 N standard ammonium thiocyanate (NH CNS) 0.1 N standard silver nitrate (AgNO Nitric acid concd. (HNO l M sodium bisulfite (NaHSO Ferric alum indicator, satd. soln. (FeNH (SO .12H O) Procedure: Weigh approximately 1 g. sample to the nearest milligram and dissolve it in approximately 100 ml. distilled water. This amount of Iodophor will consume approximately 15-20 ml. of 0.1 N silver nitrate solution; when testing dilute solutions of Iodophors, multiply this amount (1 g.) by the dilution factor.

Add dropwise the 1 M solution of sodium bisulfite until the iodine color has disappeared completely. Titrate with 0.1 N silver nitrate solution until no further precipitate forms; add an excess of 5 ml. Then add ml. concentrated nitric acid.

Add approximately 10 ml. of the ferric alum indicator solution and back-titrate with 0.1 N ammonium thiocyanate until the characteristic reddish-brown end point is reached.

Calculations 1 Net ml. 0.1 N AgNO =mL AgNO ml. NHiCNS (2) Percent total iodide net ml. AgNO normality AgNO 12.692 grams of sample The combination or sum of these two procedures accounts for about 98% of the iodine dissolved in the nonionic surface active agent, the remainder being either (a) lost due to vapor pressure of iodine in compounding or (b) chemically combined with the nonionic surface active agent. While the amount of a detectible iodine which is present as available iodine will vary depending on the particular nonionic surface active agent used, it has been found that with alkylphenol-ethylene oxide surface active agent, approximately 75 to 80% of the iodine will be present as available iodine.

The novel products of the present invention can be prepared by intimately mixing elemental iodine with a mixture of water-soluble and water-insoluble alkylphenolethylene oxide nonionic surface active agents preferably while slightly heating, e.g. to about 60 C. in order to hasten dissolution of the iodine.

The details of the present invention will be apparent to those skilled in the art from consideration of the following examples.

EXAMPLE I In a glass vessel equipped with an efficient stirrer, there was added two parts by weight of water-insoluble nonionic surface active agent obtained by condensing 1 molar proportion of nonylphenol with 4 molar proportions of ethylene oxide and 8 parts by weight of a water-soluble nonionic surface active agent obtained by condensing 1 molar proportion of nonylphenol with about molar proportions of ethylene oxide. To the thus obtained mixture there was then added 3.3 parts by weight of sufiicient available elemental iodine (resublimed crystals) and the whole heated to 60 C. with stirring for 1 hours. There was thus obtained a free flowing viscous liquid, dark brown or mahogany in color. This product (which is referred to below as Iodophor.IA) on potentiometric titration with standardized sodium thiosulfate analyzed about 20% available iodine.

This product, Iodophor 1A, was then tested for bacteriological activity on E. coli and M. pyogenes var. aureus by the Chambers Modification of the Weber-Black Test (Journal Milk Food Technology 19, No. 7, July 1956). A stock solution containing by analysis 175 p.p.m. available iodine was prepared from the foregoing Iodophor IA, and was used to make up the test concentrations. The test dilutions were plated within seconds after pipetting into plates and the plates were then incubated at 35 C. for 48 hours before the counts were recorded. The precautions and controls suggested in the method were followed. Phosphoric acid was used to main an acid pH. The results were as follows:

Table I PLATE COUNT OF SURVIVING ORGANISMS PER MILLI- LITER OF TEST SOLUTION Escherichai coli (ATCC-ll229) Ill. pyogenes var. auraus (FDA-209 NICO-6538) Lutial count 44,000,000/ml.

A 99.999% kill was obtained at 5 p.p.m. available iodine.

In contrast with the above described composition, it was found that when 7.5 parts by weight of a watersoluble nonionic surface active agent obtained by condensing 1 molar proportion of nonylphenol with about 8-9 molar proportions of ethylene oxide was mixed with about 2.5 parts by weight of iodine crystals and the mixture stirred with heating for 1 /2 hours. The resulting product (which is referred to below as Iodophor 18) was a non-pourable viscous paste. Likewise, when 7.5 parts of nonionic surface active agent obtained by condensing 1 molar proportion of nonylphenol with 15 molar proportions of ethylene oxide, e.g. the same water-soluble nonionic surface active agent employed as one component of the foregoing composition, was mixed with 2.5 parts by weight of elemental iodine by stirring at 60 C. for 1 /2 hours. The resulting product (referred to below as Iodophor IC) was an even more viscous non-pourable paste.

All three products (Iodophor IA, IB and IC) were then formulated into materials giving about 1.75% available iodine by mixing 8.75 parts by weight of each Iodophor product IA, IB, and IC with 10 parts by weight of phosphoric acid and 81.25 parts by weight of distilled water. Samples of the thus obtained formulations were stored in ordinary flint glass sample bottles. The composition containing Iodophor IA was stable on storage; that containing Iodophor IB separated into two liquid phases within two hours standing; that containing Iodophor IC formed a slight sediment on standing overnight.

EXAMPLE II Samples of Iodophors comprising a combination of alkyl-phenol-ethylene oxide nonionic surface active agents and elemental iodine were prepared in the following manner.

An amount of nonionic surface active agents shown in Table II and the amount of iodine crystals shown therein were mixed with stirring in a glass vessel for 1 /2 hours While heating to 60 C. in order to obtain the concentrate shown in the table. Each of these concentrates was then formulated with phosphoric acid and distilled water to give consumer type products containing 1.75% available iodine. It will be noted that only products in which a mixture of a water-soluble nonionic surface active agent and a water-insoluble nonionic surface active agent, i.e. products Iodophor 2B, 2C, 2E, 2F and 2G were stable on standing, e.g. there was no phase separation or formation of sediment. Samples of three products Iodophor 2B, 2C and 2E were also subjected to prolonged aging tests for 38 days at room temperature in both clear and in amber glass bottles. There was very little loss in available iodine under these conditions the available iodine content of these samples, as determined by analysis, being 1.76% at the start of this test and 1.74% after 38 days storage at the conclusion of the test. Portions of the same solutions were also stored in glass bottles at 50 C. in a thermostatically controlled oven. This gave a decrease in available iodine content from 1.78 to 1.67% on 38 days storage. However, after an additional 32 days storage no further loss of available iodine occurred as samples analyzed at the end of that period showed 1.67% available iodine.

Table II 6 itself form a stable product in water when combined with iodine, but some of the ethylene oxide content must be present in a nonionic surface active agent in which the ethylene oxide content is less than the average ethylene oxide content of all nonionics used being, however, within the range of to 90 but with at least about 15% of the nonionic used having an ethylene oxide content of less than 60%.

These novel Iodophor compositions comprising a combination of iodine with a mixture of a water-soluble and water-insoluble alkylphenol-ethylene oxide type nonionic surfactant readily lend themselves either for direct use as germicidal compositions or for formulation into use type germicidal composition formulations. In such further formulations they are, as previously indicated, combined with acid, preferably phosphoric acid, and further, diluted with water. In the preparation of such use type formulations additional alkylphenol-ethylene oxide nonionic surfactants of the water-soluble type may be incorporated so long as the total nonionics in the final formulation has an ethylene oxide content of at least 60% by weight.

In use type formulations intended primarily for sanitation such as those used in rinse waters for dishes, glasses, textiles and the like, where high detergency is not desired the weight of available iodine may be high as compared with the total weight of the nonionic surfactant in the final formulation. Where the final formulation is intended not only for sanitizing, but also for detergent operations, it is desirable that the weight of the total nonionic surfactant be high as compared with the weight of the total iodine. This ratio of weight of the total nonionic surfactant to the weight of available iodine is at Iodophor Concentrate Formulation Sample No 2A 2B 2C 2D 2E 2F 2G Nonyl phenol reacted with 4 moles of ethylene oxide (00 430) g 0 32 45. 8 22. 3 14. 4 14. 4 8-9 moles of ethylene oxide (00 630 .g 86 15 moles of ethylene oxide (00 73 0 54 75 57. 6 57. 6 30 moles of ethylene oxide 0 40. 2 52. 7 45. 8 Iodine mg... 14 14 14 25 25 28 28 Percent b weight of ethylene oxide in total nonionics 63. 8 63.8 63. 8 75 74 68. 5 75. 6 Percent Available Iodine present in concentrate (by analysis) 11. 5 11. 42 11. 61 19. 85 18.35 21 13. 8 Iodophor ratio (nonionic/percent available iodine) 7. 46 7. 52 7. 40 3. 98 4. 08 3. 44 5.

Use" Strength Formulation of the Above Concentrates Having 1.75% Available Iodine Amount of Above Iodophor use 17. 5 17.5 17.5 8. Phosphoric Acid 10 10 10 Distilled water 72. 5 72. 5 81. 25 Stability- Stable Stable Unstable 81. 25 81. 25 77. 25 Stable Stable Stable ethylene oxide content of this amount (60%) does not 75 times called in the art the Iodophor ratio which may be determined as follows:

Wt. of total nonionic surfactant Wt. of the available iodine As indicated, for products desired primarily for sanitizing a low Iodophor ratio is desirable, whereas where products intended for both detergency and sanitation a high Iodophor ratio is desirable. By reference to Table II above, it will be seen that in products 2E, 2F and 2G, the Iodo- Iodophor ratio 7 phor ratio is 4.08, 3.44, 5.65 respectively. These products thus lend themselves, particularly for use as sanitizing agents in rinses for dishes, glasses or textiles. On the other hand, products 2B and 20 have an Iodophor ratio of 7.52 and 7.4 respectively. These latter products when added in equal amounts to wash or rinse water will thus exhibit superior detergency as compared with the same amount of products 2E, 2F and 2G. The low Iodophor ratio of products 2E, 2F and 2G is particularly desirable in products intended for use in rinse water and so forth since due to the relatively small amount of surfactant present therein, such products when employed in rinse waters has less tendency to foam and, therefore, a product readily drains from glass ware and the like rinsed in it. However, where foaming is a problem and a product, having greater detergency than those having a low Iodophor such as products 2E, 2F and 2G of Table II, is desired, the amount of foam may be decreased by incorporating a small amount of a nonionic surface active agent obtained by condensing 1 molar proportion of an alkylphenol with about 1 molar proportion of ethylene oxide (i.e. in the case of a 1:1 nonylphenol-ethylene oxide condensate a product which contains about 16.6% ethylene oxide). The effect of the addition of nonylphenoxy ethanol in Iodophor IA above is shown in Table III below. The Ross-Miles foam test was used to obtain the data recorded in this table. A similar depression in foaming tendency was also observed on the use of a pressure-spray technique to simulate industrial dishwashing practices.

Table III EFFECT OF NONYLPHENOXYETHANOL IN REDUCING THE FOAM OF IODOPHOR IA BY ROSS-MILES FOAM TEST AT 120 F. AND 100 P.P.M. AVAILABLE IODINE While as mentioned previously the detergent power of the final wash or rinse water produced by adding a given amount of a given Iodophor composition to a given amount of water will vary in direct proportion to the Iodophor Ratio of the Iodophor composition. It must also be borne in mind that in formulating any particular consumer type of product the particular use strength or iodine content of the final wash or rinse water must be borne in mind in setting the Iodophor ratio of the formulated product. Thus, in order to produce a use formulation having 0.8% available iodine, 4 parts by weight of the Iodophor IA above, was mixed with 4.25 parts by weight of 100% phosphoric acid, 5 parts by weight of the nonionic surfactant obtained by condensing 1 molar proportion of nonylphenol with about moles of ethylene oxide and 86.75 parts by weight of water. While this product has a relatively high Iodophor ratio of 9921, it may be used as an effective sanitizing or germicidal rinse if relatively small amounts are added to the final rinse water. For use on non-porous hard surfaces, 4 to 8 oz. of the above use formulation when added to 10 gallons of water produce final rinse water containing 25 to 50 p.p.m. of iodine. For porous surfaces such as blankets where a somewhat higher iodine content in the water is desirable, 8 to 16 oz. of the above use formulation should be added per 10 gallons of water so as to provide 50 to 100 p.p.m. of iodine in the rinse water.

In a similar manner, a general purpose cleaner having low foam can be formulated from Iodophor IA above by mixing 8.75 parts of Iodophor IA with 8.5 parts by weight of phosphoric acid, 3 parts by weight of the condensate of 1 mole of nonylphenol with 1 mole of ethylene oxide, and 5.75 parts by weight of the condensate of 1 mole of nonylphenol with about 30 moles of ethylene oxide and 74 parts by weight of water. This use formulation has 1.75% available iodine, and an Iodophor ratio of 8.6 (slightly lower than the immediately preceding formulation) and an acid ratio of 4.8. However, due to its greater content of surfactant it can be used effectively for general cleaning. A final wash water of 25 to 50 p.p.m. of iodine is obtained by adding 2 to 3 /3 oz. of the above formulation to 10 gallons of water. For cleaning of porous surfaces, an iodine content of wash water of 50 to 100 p.p.m. iodine is desirable so that from 3 /3 to 7 /3 oz. of the above formulation to 10 gallons of water should be used. On the other hand products having a lower Iodophor ratio may be desired as a combined detergent and germicide where a high iodine content is desired in the final wash water as in hospitals etc. For a use formulation having good cleaning power was formulated by mixing 8.75 parts of Iodophor IA with 8.50 parts by weight of phosphoric acid, 5.0 parts by weight of nonionic surfactant obtained by condensing nonylphenol with about 30 moles of ethylene oxide and 77.75 parts by weight of water. This product which in the above use formulation had 1.75% available iodine, an Iodophor ratio of 6.5 and an acid ratio of 4.8 was particularly effective where good sanitizing and complete germicidal kill was desired. For non-porous hard surfaces in hospitals etc. 5% oz. of the above formulation per 10 gallons of Water may be used which will provide a wash water having 75 p.p.m. of iodine. For cleaning surgical instruments which are simultaneously sterilized by boiling, 7 /3 to 9% oz. of the above use formulation per 10 gallons of water may be used which will provide 100 to p.p.m. of iodine in the wash water. For porous surfaces such as hospital sheets or blankets, bandages and the like, 11 oz. of the above formulation per 10 gallons of water will provide a wash water having p.p.m. of iodine.

While the condensates of nonylphenol with ethylene oxide have been specifically referred to in the above examples as a preferred type of alkylphenol-ethylene oxide nonionic surfactant, it should be understood that other alkylphenol-ethylene oxide condensates may be employed if desired. The nonylphenol-ethylene oxide condensates have been preferred due to their commercial availability. However, a number of other condensates of ethylene oxide with other alkylphenols have been investigated and found to be the equivalent of the nonylphenol-ethylene oxide condensate previously described. The alkylphenol-ethylene oxide condensates which are employed in the prment invention may be represented by the following general formula:

wherein R represents an alkyl group and R and R" represent hydrogen or an alkyl group, the total number of alkyl carbon atoms in R, R and R" being at least 6 and more, preferably at least 8 and may be as high as 24, n is an integer representing the number of moles of ethylene oxide condensed with the particular alkylphenol employed. As previously indicated, one of the nonionic surfactants of this type which is employed should be a product containing less than 55% by weight of ethylene oxide and the other nonionic surfactant should be a product containing more than 60% ethylene oxide. The two surfactants being mixed in such proportions with the mixture of nonionics employed contains at least 60% ethylene oxide. A wide variety of such alkylphenol-ethylene oxide condensates are known in the prior art, many of them being described for example in US. Patent 2,213,477, a disclosure of which is incorporated herein by reference. Illustrative of the alkylphenols whose condensates with ethylene oxide may be used may be mentioned dibutylphenol, dibutylcreso l, diamylphenol, diamylcresol, octylphenol, isooctylphenol, nonylphenol, decylphenol, undecylphenol, dodecylphenol, penadecylphenol, octadecylphenol, dinonylphenol, didodecylphenol and the corresponding cresols. It should also be understood that, if desired, the water-insoluble alkyl-phenolethylene oxide nonionic surfactant may be derived from one alkylphenol and the water-soluble alkylphenol-ethylene oxide condensate may be derived from a different alkylphenol. Also as illustrated by the above examples, it is possible to use a mixture of water-insoluble alkylphenol-ethylene oxide condensates and a mixture of watersoluble alkylphenol-ethylene oxide condensates so long as the percentage of ethylene oxide in the specific condensates and in the mixture of such nonionic surfactants used is within the percentages above specified.

We claim:

1. A water soluble germicidal composition comprising a combination of iodine with a mixture of nonionic alkyl phenol-ethylene oxide condensate surface active agents characterized in that the nonionic surface active agents in said composition are a mixture of a water insoluble nonionic alkyl phenol-ethylene oxide condensate surface active agent having an ethylene oxide content of less than 55% by weight and a water soluble nonionic alkyl phenolethylene oxide condensate surface active agent having an ethylene oxide content of more than 60% by weight, the ethylene oxide content of said mixture of water insoluble and water soluble nonionic surface active agents being more than 60% by weight of said mixture.

2. A water soluble concentrated germicidal composition comprising a combination of at least about 20% by weight of iodine with a mixture of nonionic alkyl phenolethylene oxide condensate surface active agents, said mixture of nonionic surface active agents consisting essentially of a minor amount of at least about 15% by weight of the total of said nonionic surface active agents of a water insoluble nonionic alkyl phenol-ethylene oxide condensate surface active agent having an ethylene oxide content of less than 55 by weight and a major amount of a Water soluble nonionic alkyl phenol-ethylene oxide condensate surface active agent having an ethylene oxide content of more than 60% by weight, the ethylene oxide content of said mixture of water insoluble and water soluble nonionic surface active agents being more than 60% by weight of said mixture.

3. A water soluble concentrated germicidal composition comprising a combination of about 25 parts by weight of iodine with about 75 parts by weight of a mixture of nonionic alkyl phenol-ethylene oxide condensate surface active agents, said mixture of nonionic surface active agents consisting essentially of about 1 part by weight of the water insoluble nonionic surface active condensate of about 1 molar proportion of nonyl phenol with about 4 molar proportions of ethylene oxide and 4 6 parts by weight of the water soluble nonionic surface 4. A germicidal composition consisting essentially of an aqueous solution containing such an amount of a nonoxidizing mineral acid that said solution has a pH below 4 and an available iodine content of at least about 0.5% by weight of a mixture of nonionic alkyl phenolethylene oxide condensate surface active agents characterized in that the nonionic surface active agents in said composition are a mixture of a water insoluble nonionic alkyl phenol-ethylene oxide condensate surface active agent having an ethylene oxide content of less than 55% by weight and a water soluble nonionic alkyl phenolethylene oxide condensate surface active agent having an ethylene oxide content of more than by weight, the ethylene oxide content of said mixture of water insoluble and water soluble nonionic surface active agents being more than 60% by weight of said mixture.

5. A germicidal composition consisting essentially of an aqueous solution containing such an amount of a nonoxidizing mineral acid that said solution has a pH below 4 and an available iodine content of at least about 0.5% by Weight of a mixture of nonionic alkyl phenol-ethylene oxide condensate surface active agents, said mixture of nonionic surface active agents consisting essentially of a minor amount of at least about 15 by weight of the total of said nonionic surface active agents of a water insoluble nonionic alkyl phenol-ethylene oxide condensate surface active agent having an ethylene oxide content of less than 55 by weight and a major amount of a water soluble nonionic alkyl phenol-ethylene oxide condensate surface active agent having an ethylene oxide content of more than 60% by Weight, the ethylene oxide content of said mixture of water insoluble and water soluble nonionic surface active agents being more than 60% by weight of said mixture.

6. The composition as defined in claim 5 wherein the mineral acid specified is phosphoric acid.

7. A germicidal composition consisting essentially of an aqueous solution containing such an amount of a nonoxidizing mineral acid that said solution has a pH below 4 and an available iodine content of at least about 0.5% by weight of a combination of about 25 parts by weight of iodine with about parts by weight of a mixture of nonionic alkyl phenol-ethylene oxide condensate surface active agents, said mixture of nonionic surface active agents consisting essentially of about 1 part by weight of the water insoluble nonionic surface active condensate of about 1 molar proportion of nonyl phenol with about 4 molar proportions of ethylene oxide and 4 parts by weight of the water soluble nonionic surface active condensate of about 1 molar proportion of nonyl with about 15 molar proportions of ethylene oxide.

8. The composition as defined in claim 7 wherein the mineral acid specified is phosphoric acid.

References Cited in the file of this patent UNITED STATES PATENTS 2,710,277 Shelanski et al. June 7, 1955 2,743,208 Marcus et al. Apr. 24, 1956 2,759,869 Sutton et a1 Aug. 21, 1956 

1. A WATER SOLUBLE GERMICIDAL COMPOSITION COMPRISING A COMBINATION OF IODINE WITH A MIXTURE OF NONIONIC ALKYL PHENOL-ETHYLENE OXIDE CONDENSATE SURFACE ACTIVE AGENTS CHARACTERIZED IN THAT THE NONIONIC SURFACE ACTIVE AGENTS IN SAID COMPOSITION ARE A MIXTURE OF A WATER INSOLUBLE NONIONIC ALKYL PHENOL-ETHYLENE OXIDE CONDENSATE SURFACE ACTIVE AGENT HAVING AN ETHYLENE OXIDE CONTENT OF LESS THAN 55% BY WEIGHT AND A WATER SOLUBLE NONIONIC ALKYL PHENOLETHYLENE OXIDE CONDENSATE SURFACE ACTIVE AGENT HAVING AN ETHYLENE OXIDE CONTENT OF MORE THAN 60% BY WEIGHT, THE ETHYLENE OXIDE CONTENT OF SAID MIXTURE OF WATER INSOLUBLE AND WATER SOLUBLE NONIONIC SURFACE ACTIVE AGENTS BEING MORE THAN 60% BY WEIGHT OF SAID MIXTURE. 